The invention relates to a light path switching indicator for optical instruments.
A high performance optical instrument such as a microscope is equipped with a number of branch paths, including a viewfinder path, a photometric path, a photographing path and the like. Unless a clear indication of the switching of the light paths is given, an incorrect manipulation may often be performed without being noticed, with a result that the intended operation can not be accomplished, thereby requiring an otherwise unnecessary repeated operation of the instrument. In particular, when taking pictures, a wrong operation may result in a photographing operation with unloaded film or taking wrong pictures to cause a waste of the film.
In order to overcome such disadvantages and to prevent a wrong operation during the switching process, the prior practice has been to recognize the position of a light path switching shaft or operating handle, or letters and colored markings associated therewith, before initiating an intended operation. However, increasingly complicated optical systems together with the incorporation of various kinds of mechanisms have resulted in a complex structure of the overall optical system, which prevents the disposition of various switching shafts and operating handles in a closely spaced and easily recognizable manner from being achieved. If the disposition of these members to bring them closer together were possible, the resulting arrangement will become extremely complex, disadvantageously causing an increased cost.
When taking pictures, the film size varies with the type of a camera being used, and therefore it is customary to provide a number of masks corresponding to all of the sizes within a viewfinder and to utilize only that mask which is associated with the film being used. However, the presence of a number of masks hinders an immediate recognition of which mask corresponds to the film being used.